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PubMed1993

Volume recruitment maneuvers are less deleterious than persistent low lung volumes in the atelectasis-prone rabbit lung during high-frequency oscillation.

OBJECTIVES: To test whether the pulmonary risk of repeated volume recruitment is greater or less than the risk associated with unreversed atelectasis during 6 hrs of high-frequency oscillatory ventilation in the atelectasis-prone rabbit lung. DESIGN: Prospective, controlled, randomized comparison over 6 hrs of ventilator management. SETTING: Laboratory. SUBJECTS: Twenty-eight adult New Zealand white male rabbits (weight 2.3 to 2.8 kg). BACKGROUND: Controversy exists over whether high-frequency oscillatory ventilation should be used with volume recruitment maneuvers in the atelectasis-prone lung, or be used at low mean and peak pressures without volume recruitment to avoid the risks of even transient pulmonary overdistention. Potential risks and benefits accompany both alternatives. INTERVENTIONS: We evaluated the pulmonary effects of three high-frequency oscillatory ventilation protocols in anesthetized rabbits made surfactant deficient by saline lavage, using animals ventilated with conventional positive-pressure ventilation with positive end-expiratory pressure as a reference group; n = 5 in each group. The three high-frequency oscillatory ventilation groups were ventilated for 6 hrs at 15 Hz (900 breaths/min), FIO2 = 1.0. The repeated stretch group received 15-sec sustained inflations at 30 cm H2O mean airway pressure every 20 mins, with maintenance mean airway pressure sufficient to keep PaO2 > 350 torr (46.7 kPa). The repeated deflation group was maintained at levels that produced PaO2 70 to 120 torr (9.3 to 16 kPa), with the endotracheal tube opened to atmospheric pressure for 15 secs every 20 mins. Animals in the repeated stretch after deflations group were managed as in the repeated stretch protocol but each sustained inflation was preceded by a 15-sec deflation to functional residual capacity. The conventional positive-pressure ventilation group was ventilated at rates of 30 to 100 breaths/min, keeping PaO2 70 to 120 torr (9.3 to 16 kPa). End-points included terminal functional residual capacity and a compliance index computed from respiratory system pressure-volume curves. MEASUREMENTS AND MAIN RESULTS: After 6 hrs of ventilation, respiratory system compliance in the repeated stretch group had returned to control values (1.35 +/- 0.18 [SD] mL/kg/cm H2O). Respiratory system compliance was significantly less than this number in both the repeated deflation (0.89 +/- 0.08) and repeated stretch after deflations (1.24 +/- 0.22) groups (p < .05). Respiratory system compliance after 3 hrs of conventional positive-pressure ventilation decreased to 0.34 +/- 0.10 mL/kg/cm H2O. Functional residual capacity changes paralleled these changes of respiratory system compliance. CONCLUSIONS: These data demonstrate that the potential pulmonary risk of repeated lung stretch during volume recruitment is significantly less than the damage arising from the avoidance of such maneuvers in lungs in which alveolar recruitment is possible. We conclude that sustained inflations during high-frequency oscillatory ventilation produce the benefits of increased oxygenation for a given mean airway pressure plus decreased progression of lung injury.

Airway Resistance↗

PubMed1987

Lung mechanics, gas exchange, pulmonary perfusion, and hemodynamics in a canine model of acute Pseudomonas pneumonia.

Acute bilateral hemorrhagic pneumonia was induced in 6 dogs (pneumonia group) by endotracheal inoculation with Pseudomonas aeruginosa. Measurements of lung mechanics, gas exchange, distribution of pulmonary blood flow, and hemodynamics were made prior to inoculation and 5 hr later when pneumonia was established. These findings were compared to the same measurements in 6 other dogs inoculated with a sterile broth (control group). While there were no significant changes in lung mechanics in the control group, pneumonia caused a significant and proportional reduction (42%) in total lung capacity (TLC) and functional residual capacity (FRC). Although tidal lung compliance was reduced in the pneumonia group, neither the specific compliance nor the deflation pressure-volume curve, with lung volume expressed as a percentage of observed TLC, changed significantly. Pneumonia caused marked hypoxemia with a mean increase in shunt and venous admixture of 35% and 52%, respectively, while the control group developed only minimal abnormalities in gas exchange. Perfusion of the consolidated lung region, determined by radioactive microspheres and expressed as a percentage of total pulmonary blood flow, showed a small but significant decrease from baseline (53 +/- 13%) to established pneumonia (44 +/- 14%), while no change in lobar perfusion was seen in the control group. Only the infected animals showed significant changes in hemodynamics with a rise in cardiac output and fall in mean systemic arterial pressure and vascular resistance. We conclude that acute experimental Pseudomonas pneumonia causes reduction of FRC by filling of alveoli with inflammatory exudate and further reduction of TLC by preventing these alveoli from inflating at higher lung volumes without evidence for a change in the elastic properties of the remaining inflated lung; marked hypoxemia caused by maintenance of perfusion of consolidated lung with reduced or absent ventilation; and a hyperdynamic septic hemodynamic state similar to that seen in humans.

Animals↗

PubMed1990

Deformation of the dog lung in the chest wall.

Data on the shape of the chest wall at total lung capacity (TLC) and functional residual capacity (FRC) were used as boundary conditions in an analysis of the deformation of the dog lung. The lung was modeled as an elastic body, and the deformation of the lung from TLC to FRC caused by the change in chest wall shape and gravity were calculated. Parenchymal distortions, distributions of regional volume at FRC as a fraction of the volume at TLC, and distributions of surface pressure at FRC are reported. In the prone dog there are minor variations in fractional volume along the cephalocaudal axis. In transverse planes opposing deformations are caused by the change of shape of the transverse section and the gravitational force on the lung, and the resultant fractional volume and pleural pressure distributions are nearly uniform. In the supine dog, there is a small cephalocaudal gradient in fractional volume, with lower fractional volume caudally. In transverse sections the heart and abdomen extend farther dorsally at FRC, squeezing the lung beneath them. The gradients in fractional volume and pleural pressure caused by shape changes are in the same direction as the gradients caused by the direct gravitational force on the lung, and these two factors contribute about equally to the large resultant vertical gradients in fractional volume and pleural pressure. In the prone position the heart and upper abdomen rest on the rib cage. In the supine posture much of their weight is carried by the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Growth potential of porcine reduced-size mature pulmonary lobar transplants.

The use of mature pulmonary lobes for pediatric lung transplantation has recently been described. Successful application of this technique could help alleviate the pediatric donor lung shortage. Whether an already mature lobe can grow by forming new alveolar units after transplantation into a developing recipient is not known. We therefore measured functional residual capacity, fixed lung volume and weight, alveolar size and air space volume percent, and total number of alveoli in mature left lower lobe porcine lung transplants 12 weeks after transplantation into growing piglets. Comparisons were made with nontransplanted mature left lower lobes to determine if functional or morphologic growth had occurred after transplantation. The transplanted and control lobes were all taken from 6-month-old animals (mean body weight 105 +/- 4 kg). Recipients of the transplanted lobes were 9 weeks old and weighed 22 +/- 2 kg. By the end of the 12-week holding period, the recipient animals increased their body weight approximately fourfold (85 +/- 4 kg). No significant differences were seen in functional residual capacity or morphologic analysis of total alveolar number and alveolar size between the transplanted and nontransplanted lobes (p = not significant). Although the reduced-size mature porcine lobar transplants did not display a significant increase in either functional residual capacity or total alveolar number, there was significant growth of the transplanted mature lobes as determined by fixed volume and total lobar weight (p < or = 0.05 versus control animals).

Animals↗

PubMed2000

Timing of antenatal corticosteroids and neonatal pulmonary mechanics.

OBJECTIVE: We sought to compare lung mechanics in infants treated with multiple courses of antenatal corticosteroids with those in matched control infants delivered >7 days from dosing and those of matched untreated infants. STUDY DESIGN: Eighteen infants who received multiple courses of corticosteroids and were delivered within 7 days of dosing were matched with 18 infants who received 1 course of corticosteroids >7 days before delivery (remote) and 18 untreated infants. Respiratory compliance and functional residual capacity were measured within 36 hours. Differences were compared by analysis of variance. RESULTS: Infant demographics were similar. Respiratory compliance was higher in the multiple-course group than in the remote or untreated group (P <.02). Functional residual capacity was higher in the multiple-course group than in the untreated group (P <.05) but similar to that found in the remote group. CONCLUSION: Babies delivered after multiple courses of corticosteroids and within 7 days of dosing demonstrated improved respiratory compliance compared with untreated and remotely treated infants. This suggests that the enzyme system responsible for surfactant production can be repetitively induced despite prior treatment with corticosteroids. The increased functional residual capacity in remotely treated infants may reflect a maturation of lung architecture independent of surfactant production.

Betamethasone↗

PubMed1986

Effect of pleurotomy on pulmonary function after median sternotomy.

To determine whether pleurotomy during median sternotomy worsens postoperative pulmonary function, patients whose pleurae remained intact (N = 7) were compared with those whose pleural spaces were entered during median sternotomy (N = 31). Thirty-eight adults performed spirometry and N2 washout to determine functional residual capacity preoperatively and 2, 24, 48, and 72 hours after extubation. Two mediastinal drainage tubes were placed in every patient; no pleural drainage tubes were inserted. Chest roentgenograms were performed preoperatively and 24 and 72 hours after extubation. Preoperatively, functional residual capacity, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and FEV1/FVC did not differ between groups. Postoperatively, in all patients developed a restrictive pulmonary defect, but mean functional residual capacity, FVC, FEV1 and FEV1/FVC did not differ between groups. In contrast to earlier reports, entering the pleural space did not worsen the restrictive pulmonary defect that results from median sternotomy when direct pleural drainage was avoided.

Adult↗

PubMed2001

Gravity effects on regional lung ventilation determined by functional EIT during parabolic flights.

Gravity-dependent changes of regional lung function were studied during normogravity, hypergravity, and microgravity induced by parabolic flights. Seven healthy subjects were followed in the right lateral and supine postures during tidal breathing, forced vital capacity, and slow expiratory vital capacity maneuvers. Regional 1) lung ventilation, 2) lung volumes, and 3) lung emptying behavior were studied in a transverse thoracic plane by functional electrical impedance tomography (EIT). The results showed gravity-dependent changes of regional lung ventilation parameters. A significant effect of gravity on regional functional residual capacity with a rapid lung volume redistribution during the gravity transition phases was established. The most homogeneous functional residual capacity distribution was found at microgravity. During vital capacity and forced vital capacity in the right lateral posture, the decrease in lung volume on expiration was larger in the right lung region at all gravity phases. During tidal breathing, the differences in ventilation magnitudes between the right and left lung regions were not significant in either posture or gravity phase. A significant nonlinearity of lung emptying was determined at normogravity and hypergravity. The pattern of lung emptying was homogeneous during microgravity.

Adult↗

PubMed1995

Human chest wall function while awake and during halothane anesthesia. I. Quiet breathing.

BACKGROUND: Data concerning chest wall configuration and the activities of the major respiratory muscles that determine this configuration during anesthesia in humans are limited. The aim of this study was to determine the effects of halothane anesthesia on respiratory muscle activity and chest wall shape and motion during spontaneous breathing. METHODS: Six human subjects were studied while awake and during 1 MAC halothane anesthesia. Respiratory muscle activity was measured using fine-wire electromyography electrodes. Chest wall configuration was determined using images of the thorax obtained by three-dimensional fast computed tomography. Tidal changes in gas volume were measured by integrating respiratory gas flow, and the functional residual capacity was measured by a nitrogen dilution technique. RESULTS: While awake, ribcage expansion was responsible for 25 +/- 4% (mean +/- SE) of the total change in thoracic volume (delta Vth) during inspiration. Phasic inspiratory activity was regularly present in the diaphragm and parasternal intercostal muscles. Halothane anesthesia (1 MAC) abolished activity in the parasternal intercostal muscles and increased phasic expiratory activity in the abdominal muscles and lateral ribcage muscles. However, halothane did not significantly change the ribcage contribution to delta Vth (18 +/- 4%). Intrathoracic blood volume, measured by comparing changes in total thoracic volume and gas volume, increased significantly during inspiration both while awake and while anesthetized (by approximately 20% of delta Vth, P < 0.05). Halothane anesthesia significantly reduced the functional residual capacity (by 258 +/- 78 ml), primarily via an inward motion of the end-expiratory position of the ribcage. Although the diaphragm consistently changed shape, with a cephalad displacement of posterior regions and a caudad displacement of anterior regions, the diaphragm did not consistently contribute to the reduction in the functional residual capacity. Halothane anesthesia consistently increased the curvature of the thoracic spine measured in the saggital plane. CONCLUSIONS: The authors conclude that (1) ribcage expansion is relatively well preserved during halothane anesthesia despite the loss of parasternal intercostal muscle activity; (2) an inward displacement of the ribcage accounts for most of the decrease in functional residual capacity caused by halothane anesthesia, accompanied by changes in diaphragm shape that may be related to motion of its insertions on the thoracoabdominal wall; and (3) changes in intrathoracic blood volume constitute a significant fraction of delta Vth during tidal breathing.

Adult↗

PubMed1989

Changes in pharyngeal properties after uvulopalatopharyngoplasty.

Uvulopalatopharyngoplasty is a commonly used modality for surgical treatment of snoring and obstructive sleep apnea. Although this procedure is thought to alter pharyngeal properties, its effect on pharyngeal mechanics has not been studied. The acoustic reflection technique was used to measure pharyngeal area at functional residual capacity and residual volume before and after uvulopalatopharyngoplasty in eight patients referred because of loud snoring. We also calculated the lung volume dependence of pharyngeal area, defined as the percent change in pharyngeal area between functional residual capacity and residual volume, normalized to the area at functional residual capacity. This parameter, which may be related to pharyngeal collapsibility, was obtained before and after uvulopalatopharyngoplasty. Preoperative sleep studies showed that one patient had obstructive sleep apnea (apnea index greater than 10). Uvulopalatopharyngoplasty resulted in a significant increase (p less than 0.01) in pharyngeal area (from 3.14 +/- 0.71 cm2 to 4.25 +/- 1.07 cm2) and residual volume (from 2.49 +/- 0.53 cm2 to 3.91 +/- 0.83 cm2). Following uvulopalatopharyngoplasty, the pharynx became stiffer, as manifested by a reduction in lung volume dependence of pharyngeal area from 19 +/- 12% to 8 +/- 13% (p less than 0.05). Six patients, including the patient with obstructive sleep apnea, reported improvement in snoring. Two patients reported worsening in snoring. One of the two was found to have reduction in pharyngeal area and lung volume dependence of pharyngeal area, and an increase in apnea index from 3 to 33. In selected snorers, uvulopalatopharyngoplasty results in improvement in snoring with a concomitant increase in pharyngeal area and a tendency toward lower pharyngeal collapsibility.

Adult↗

PubMed1992

Hyperinflation in premature infants at preschool age.

Functional residual capacity was measured by helium gas dilution in 12 children born very preterm (gestational age 25-29 weeks). The children were studied at between 4.0 and 4.6 years of age. Their results were compared to those of 12 control children who were born at term without neonatal problems. The controls were matched to the children born preterm for age, race and gender. The children born preterm had significantly increased functional residual capacity values when compared to the control subjects (p less than 0.01). Eight children born preterm were hyperinflated (functional residual capacity greater than 120% of that predicted for height) compared to only one control subject (p less than 0.01). Five children born preterm and one control had a positive response to bronchodilator administration. These results suggest infants born very preterm may suffer from chronic hyperinflation.

Birth Weight↗

PubMed1989

Transmission of sound generated by sternal percussion.

We indirectly determined the transmission path of sound generated by sternal percussion in five healthy subjects. We percussed the sternum of each subject while recording the output audio signal at the posterior left and right upper and lower lung zones. Sound measurements were done during apnea at functional residual capacity, total lung capacity, and residual volume both with the lungs filled with air and with an 80% He-20% O2 (heliox) gas mixture. Three acoustic indexes were calculated from the output sound pulse: the peak-to-peak amplitude, the peak frequency, and the mid-power frequency. We found that the average values of all indexes tended to be greater in the upper than in the ipsilateral lower lung zones. In the upper zones, peak-to-peak amplitude was greater at total lung capacity and residual volume than at functional residual capacity. Replacing air with heliox did not change these results. These experiments, together with others performed during Mueller and Valsalva maneuvers, suggest that resonance of the chest cage is the predominant factor determining the transmission of sternal percussion sounds to the posterior chest wall. The transmission seems to be only minimally affected by the acoustic characteristics of the lung parenchyma.

Adult↗

PubMed1976

[Closing volume and ventilatory distribution disturbances (author's transl)].

Ventilatory disturbances are induced by airway closure associated with an increase of the venous admixture from alveoli with a low ventilation-perfusion-ratio. Closing volume was measured by single breath nitrogen washout curves and correlated with ventilatory disturbances derived from multiple breath nitrogen washout curves and an inspiratory gas distribution index (IDI). There was present a close correlation between the closing volume in relation to the functional residual capacity and the IDI. With rising closing volume in relation to functional residual capacity a deterioration of the inspiratory gas distribution with increasing venous admixture was observed.

Adolescent↗

PubMed1993

Airway irritation produced by volatile anaesthetics during brief inhalation: comparison of halothane, enflurane, isoflurane and sevoflurane.

Eleven male volunteers were studied to compare the airway irritation produced by the four anaesthetic agents: halothane, enflurane, isoflurane and sevoflurane at two concentrations, equivalent to one and two MAC. Tidal volume, respiratory frequency and functional residual capacity changes induced by 15 sec inhalation of the anaesthetics were measured using respiratory inductive plethysmograph. Appearance of the cough reflex was also observed. The order of subjective airway irritation was evaluated by the volunteers. Inhalation of the anaesthetic agents induced a decrease in tidal volume, increase in respiratory frequency and decrease in functional residual capacity. Significant changes were considered to have occurred if tidal volume and respiratory frequency changed by more than 30% from the resting values for at least ten seconds, or if functional residual capacity changed by more than 30% of the value at resting tidal volume, for at least ten seconds. Each change was induced most frequently by isoflurane followed by enflurane, halothane and, least frequently, by sevoflurane. The orders of appearance of the cough reflex and of subjective airway irritation were similar. Sevoflurane did not elicit a cough reflex. It is concluded that sevoflurane was the least irritant anaesthetic and is considered to be the most suitable for inhalational induction of anaesthesia.

Administration, Inhalation↗

PubMed1986

Trachea and lung dimensions in nonsmoking twins: morphological and functional studies.

To compare genetic and environmental factors that determine lung function and dimensions, chest radiographs and pulmonary function were measured in 17 pairs of nonsmoking twin adolescent boys (12 monozygotic pairs and 5 dizygotic pairs). Genetic factors dominated in tracheal width and lung dimensions (height, width, and apicofissural and fissurodiaphragmatic distances) at residual volume. Genetic factors also affected forced vital capacity, functional residual capacity, forced expiratory volume in 1 s, maximum expiratory flow at 25% vital capacity, and maximum flow at 50% vital capacity-to-forced vital capacity ratio. Peak expiratory flow correlated with tracheal width at residual volume. Age correlated with lung dimensions (width and depth) but not with tracheal width. These results indicate that genetic factors determine the dimensions and function of central airways, peripheral airways, and lung parenchyma in adolescent males. The effects of genetic factors on some functional measurements (airway resistance, closing volume-to-vital capacity ratio, and phase III in single-breath N2 washout) may be masked because of poor reproducibility of the tests.

Adolescent↗

PubMed1992

Comparison of postoperative respiratory function after laparoscopy or open laparotomy for cholecystectomy.

Cholecystectomy performed via laparotomy is associated with reduction of lung volumes including functional residual capacity that may lead to postoperative hypoxia and atelectasis. Laparoscopic cholecystectomy is associated with faster recovery compared to open laparotomy and cholecystectomy. To determine whether laparoscopic cholecystectomy was associated with less pulmonary dysfunction, 20 patients (ASA Physical Status I) undergoing elective cholecystectomy were randomly assigned to surgical teams performing either laparoscopy or open laparotomy for cholecystectomy. Patients in whom one or the other surgical technique had to be performed for medical or psychologic indications were excluded from the study. A standardized anesthetic technique and postoperative analgesic regimen were used. Forced vital capacity and forced expiratory volume in 1 s; functional residual capacity determined by a closed-circuit, constant volume helium dilution technique; and arterial O2 and CO2 tensions were measured preoperatively and at 6, 24, and 72 h postcholecystectomy. Forced vital capacity and forced expiratory volume in 1 s were significantly greater (P less than 0.05) in the laparoscopy compared to the laparotomy group at 6, 24, and 72 h postoperatively. Forced vital capacity relative to preoperative values was significantly (P less than 0.05) greater in patients with laparoscopy (24 h, 70 +/- 14%; 72 h, 91 +/- 6%) compared to open laparotomy (24 h, 57 +/- 23%; 72 h, 77 +/- 14%). Similarly, forced expiratory volumes in 1 s relative to preoperative values were significantly (P less than 0.05) greater in patients with laparoscopy (24 h, 85 +/- 13%; 72 h, 92 +/- 9%) compared to open laparotomy (24 h, 54 +/- 22%; 72 h, 77 +/- 11%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1996

Mechanical significance of respiratory muscle activity in humans during halothane anesthesia.

BACKGROUND: Prior human studies have shown that halothane attenuates activity in the parasternal intercostal muscle and enhances phasic activity in respiratory muscles with expiratory actions. This expiratory muscle activity could contribute to reductions in the functional residual capacity produced by anesthesia. Termination of this activity could contribute to the maintenance of inspiratory rib cage expansion. The purpose of this study was to estimate in humans the mechanical significance of expiratory muscle activity during halothane anesthesia and to search for the presence of scalene muscle activity during halothane anesthesia that might contribute to inspiratory rib cage expansion. METHODS: Six subjects (3 males, 3 females) were studied while awake and during 1.2 MAC halothane anesthesia, both during quiet breathing and during carbon dioxide rebreathing. Respiratory muscle activity was measured using fine-wire electromyography electrodes. Chest wall configuration was determined using images of the thorax obtained by three-dimensional, fast computed tomography and respiratory impedance plethysmography. Functional residual capacity was measured by a nitrogen dilution technique. Measurements were obtained after paralysis with 0.1 mg/kg vecuronium and mechanical ventilation. RESULTS: Phasic inspiratory activity was present in the scalene muscle of four anesthetized subjects during quiet breathing and all anesthetized subjects during rebreathing. Phasic inspiratory activity was present in the parasternal intercostal muscle during halothane anesthesia in only the three female subjects and was enhanced by rebreathing; parasternal intercostal muscle activity was never present in anesthetized males. During anesthesia with quiet breathing, phasic expiratory activity was observed in the transversus abdominis muscles of only the three male subjects. Despite these differences in the pattern of respiratory muscle use, the pattern of chest wall responses to rebreathing was similar between males and females. When expiratory muscle activity was present, paralysis increased the end-expiratory thoracic volume by expanding the rib cage, demonstrating that this activity reduced thoracic volume in these subjects. Changes in thoracic blood volume were significant determinants of the change in functional residual capacity produced by paralysis. CONCLUSIONS: In humans anesthetized with 1.2 MAC end-tidal halothane, there are marked interindividual differences in respiratory muscle use during quiet breathing that may be related to sex; phasic inspiratory scalene muscle and parasternal intercostal muscle activity may contribute to inspiratory rib cage expansion in some subjects; and when present, expiratory muscle activity significantly constricts the rib cage and contributes to reductions in functional residual capacity caused by halothane anesthesia.

Adult↗

PubMed1986

Pharyngeal size in snorers, nonsnorers, and patients with obstructive sleep apnea.

We measured pharyngeal cross-sectional area and its change with alterations in lung volume in 10 subjects who snored and had obstructive sleep apnea, 6 subjects who snored and did not have obstructive sleep apnea, and 9 subjects who did not snore. Pharyngeal area was measured with use of an acoustic-reflection technique. We found that snorers with and without sleep apnea had a significantly smaller mean (+/- SE) pharyngeal cross-sectional area (4.1 +/- 0.2 and 3.7 +/- 0.9 cm2, respectively) at functional residual capacity than nonsnorers (5.4 +/- 0.5 cm2, P less than 0.025). When lung volume decreased from functional residual capacity to residual volume, both nonsnorers and snorers with sleep apnea had a decrease in pharyngeal area (from 5.4 +/- 0.5 to 4.5 +/- 0.4 cm2 and 4.1 +/- 0.2 to 3.4 +/- 0.2 cm2, respectively), whereas snorers without sleep apnea had no such decrease, suggesting that their pharynxes were less collapsible at low lung volumes. We conclude that snorers with and without sleep apnea have smaller pharyngeal cross-sectional areas than nonsnorers and that snorers with sleep apnea have a further decrease as lung volume falls.

Adult↗

PubMed1999

[Clinical and respiratory function follow-up of 39 infants treated with neonatal respiratory extracorporeal assistance].

UNLABELLED: The aim of this prospective study was to evaluate the consequences of neonatal treatment with a venovenous extracorporeal respiratory assistance. POPULATION AND METHODS: Thirty nine neonates (28 boys) with acute respiratory failure were included. Extracorporeal respiratory assistance consisted of an apnoeic oxygenation with low frequency positive pressure ventilation and extracorporeal membrane CO2 removal through a venous single canula perfusion circuit. The causes of respiratory distress were: 15 meconium aspiration syndrome, 12 respiratory distress syndrome, six hyaline membrane disease, three sepsis, two diaphragmatic hernia, and one post-surgery Mendelson syndrome. The mean duration of mechanical ventilation was 18 days, including 5 days of extracorporeal respiratory assistance. The prospective follow-up included physical examination, chest radiographs, scintigraphy and pulmonary function tests. These tests studied the following parameters: functional residual capacity by helium dilution technique, lung resistance and dynamic lung compliance by the esophageal balloon technique and blood gases with arterialized blood samples. RESULTS: The mean duration of the follow-up was 21.3 months (6 months to 5 years). Results showed in the first year 33% of children with chronic obstructive pulmonary disease and chest (X-ray abnormalities, such as bronchopulmonary dysplasia in 23% of children. Data of pulmonary function test at the end of the first year: lung resistance and functional residual capacity were within limits of predicted values for height, and dynamic lung compliance was slightly decreased; according to the analysis of the functional profile: 31% without abnormality, 41% of obstructive syndrome and 26% with restrictive pattern. Blood gases were normal in 37 children. At the end of the second year, we noticed normal functional residual capacity, an increase of lung resistance while lung compliance was normalized; functional profile was quite different: with a decrease of the number of patients without abnormality (22%) and increase of those with obstructive syndrome (56%). CONCLUSION: The percentage of abnormalities is high but these are moderate in most cases, especially if we compare with the initial seriousness of the pulmonary pathology. We suggest a regular follow-up to study the respective incidence of pulmonary disease and/or extracorporeal respiratory assistance over these abnormalities.

Acute Disease↗